Claims

1. A method of producing polysulfides comprising the step of adding elemental sulphur to an allicin-containing plant extract.

2. The method of claim 1 wherein the said plant extract is an extract of the genus Allium.

3. A method according to claim 1 further comprising the step of heating the mixture so produced.

4. A method according to claim 3 wherein the said mixture is heated to at least 60 degrees Celsius.

5. A method according to claim 3 wherein the said mixture is heated to at least 70 degrees Celsius.

6. A method according to claim 1 wherein sulphur is added to a concentration of at least 0.1% (w/w).

7. A method according to claim 1 wherein sulphur is added to a concentration of at least 1% (w/w).

8. A method of producing polysufides of increased chain length comprising a method according to claim 1 and characterised in that the pH of the mixture so produced is adjusted to be below pH 4.0.

9. A method of producing polysufides of decreased chain length comprising a method according to claim 1 and characterised by the addition of an amine.

10. A method according to claim 9 wherein the said amine is dibutyl amine.

11. A method according to claim 9 wherein the said amine is an amino acid.

12. A method according to claim 1 and, further characterised in that the pH of the mixture so produced is adjusted to be above pH 8.

13. A method of producing polysulfides substantially as describedherein.

14. A crop protection agent produced according to the method of claim 1.

15. A pharmaceutical or therapeutic composition produced according to the method of claim 1.